Thrust force sensors are used to measure in-line thrust or driving forces exerted on a rotating rod or shaft within rotary machines, in static systems, in vehicle powertrains, or in other various known applications. These sensors must be capable of operating within the harsh conditions common to industrial machinery and vehicle applications. Traditionally, these thrust force sensors are contact sensors that utilize brushes and commutators to generate signals representative of the thrust force applied to the rod or shaft. One disadvantage with these contact sensors is that they have difficulty operating in the harsh environmental conditions. Dirt, water, and other contaminants adversely effect the operation of the brushes, resulting in reduced accuracy of the thrust force measurements.
Another disadvantage with traditional contact thrust force sensor assemblies is that there is often rotational speed limits imposed as part of the operating criteria for the sensor assembly. In other words, the contact sensor assembly can only be used within a certain rotational speed operating range. If the rotational speed of the rotating shaft exceeds an upper limit of this speed operating range, the sensor may not operate accurately, or may come apart or shatter at excessive rotational speeds.
Thus, there is a need for thrust force sensors that can withstand excursions well beyond traditional full-scale measurement ranges, and which can operate in harsh environmental conditions. The sensors should be durable, reliable, and capable of operating in various applications. For example, the sensor should be easily incorporated into processing machine applications, in which rotating work pieces are subjected to either compressing or drawing operations. The sensor should also be easily incorporated into vehicle applications. For example, measuring the force compressing clutch plates would result in beneficial data such as degree of engagement, coupling characteristics, and power transfer characteristics. Further, measuring forces exerted on vehicle suspension struts would improve compensation control for ride stability.